There is a built-in tool to do this. Navigate to: Wp Admin > WooCommerce > Status > Tools : Reset WC Vendors Roles.
If the tool fails to reset the roles, a second option exists:
If you have permission and capability problems with your vendors due to other plugins that modify these permissions and need to reset them you can add the following code to your themes functions.php and then login to your site again from your my-account page.
add_filter('woocommerce_login_redirect', 'redo_roles', 10, 2); function redo_roles() { remove_role( 'pending_vendor' ); add_role( 'pending_vendor', __( 'Pending Vendor', 'wcvendors' ), array( 'read' => true, 'edit_posts' => false, 'delete_posts' => false ) ); remove_role( 'vendor' ); add_role( 'vendor', 'Vendor', array( 'assign_product_terms' => true, 'edit_products' => true, 'edit_product' => true, 'edit_published_products' => false, 'manage_product' => true, 'publish_products' => false, 'read' => true, 'upload_files' => true, 'view_woocommerce_reports' => true, ) ); }